yield from support for Deferreds, in functions wrapped with twisted.internet.defer.ensureDeferred. This will work in Python 3.4, unlike async/await which is 3.5+ (contributed by hawkowl, reviews by markrwilliams, lukasa).

The new asyncio interop reactor, which allows Twisted to run on top of the asyncio event loop. This doesn't include any Deferred-Future interop, but stay tuned! (contributed by itamar and hawkowl, reviews by rodrigc, markrwilliams)

twisted.internet.cfreactor is now supported on Python 2.7 and Python 3.5+! This is useful for writing pyobjc or Toga applications. (contributed by hawkowl, reviews by glyph, markrwilliams)

twisted.python.constants has been split out into constantly on PyPI, and likewise with twisted.python.versions going into the PyPI package incremental. Twisted now uses these external packages, which will be shared with other projects (like Klein). (contributed by hawkowl, reviews by glyph, markrwilliams)

Many
thanks to everyone who had a part in this release - the supporters of
the Twisted Software Foundation, the developers who contributed code as
well as documentation, and all the people building great things with
Twisted!